Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C231/00—Preparation of carboxylic acid amides
  • C07C231/02—Preparation of carboxylic acid amides from carboxylic acids or from esters, anhydrides, or halides thereof by reaction with ammonia or amines

Definitions

• This invention relates to an improved process for the preparation of N-acyl-aminodiacids.
• N-acyl-aminodiacids A variety of methods have been used to prepare N-acyl-aminodiacids. These include the method described in German Auslegeschrift 20 15 075 to Ajinomoto Co., Inc. There still remains a need, however, for an improved process and, in particular, a process that utilizes non-biohazard solvents and that results in improved yields.
• This invention comprises an improved process of making N-acyl-aminodiacids of Formula I: wherein:
• a particular compound is lauroyl glutamic acid (LGA) where
• the reaction in conducted in the presence of a water/alcohol mixture with a sufficient amount of base selected from the group consisting of NaOH, KOH, Na 2 CO 3 and K 2 CO 3 (particularly caustic) to form a disalt form of the compound of Formula I.
• the disalt (such as the disodium salt) is then added to an HCl solution to form the compound of Formula I.
• This invention relates to an improved method of making compounds of Formula I.
• an inert gas such as nitrogen
• the atmosphere of the vessel is then treated to create an atmosphere which is free of oxygen and which will not support combustion. This is done by periodically applying vacuum and purging the vessel with an inert gas such as nitrogen as needed to keep the atmosphere in the vessel in a state where it will not support combustion of an explosive oxygen/solvent mixture in the head space of the vessel.
• a polar organic solvent selected from the group consisting of (a) C 1 - C 6 alkyl alcohols wherein the alkyl portion may be straight or branched chain; and (b) tetrahydrofuran.
• Particular solvents of interest are methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol and tetrahydrofuran (THF).
• Preferred solvents are ethanol, n-propanol and isopropanol.
• Standard precautions should be taken with the reaction solvent (such as THF) regarding any potential for flammability.
• This charging with polar organic solvent may be done by aspirating the solvent into the vessel and is preferrably done without letting air into the vessel as a safety precaution.
• the temperature of the reaction vessel is lowered (such as by using a cooling jacket) to a temperature in the range of (-5) - (20) degrees C. and preferably 0 - 10 degrees (for example, 0 degrees).
• a nitrogen bleed is then resumed to the vessel to create a positive pressure of the inert gas.
• Sufficient caustic is added via the funnel described above to maintain the pH in the reaction vessel at a value in the range of 9 - 13, preferably at a pH of 9 - 10 initially.
• a chloride of Formula III (for example, lauroyl chloride) is being added to the reaction vessel in an amount such that:
• the pH be maintained at a value of about 10 at the outset of the addition of the chloride of Formula III and that the pH be allowed to gradually rise to a value of 12.5 - 13 during the final stages of the addition of the chloride.
• the temperature of the reaction should he maintained in the range of 0 - 10 degrees C; it is preferred that a temperature at the lower end of this range be used, such as 2 - 5 degrees C.
• the temperature can be controlled by reactor heat transfer mechanisms, such as with the use of cooling coils or a cooling jacket, and regulating the addition rate of the compound of Formula III.
• the contents of the reaction vessel are held at a temperature of 2 - 8 degrees for an additional period of time in the range of 0.5 - 2 hours (for example, 30 minutes) at a pH greater than or equal to 11, such as a pH of 11 - 12.
• reaction mixture is drowned into a mineral acid.
• the acid or some dilution of the acid may be added directly to the reaction mixture with later addition of dilution water or the reaction mixture can be poured into an acid solution, provided that in each case sufficient dilution water is included which will equal 5 - 10 times the volume of the original reaction mixture.
• Suitable acids include HCl, H 2 SO 4 and H 3 PO 4 and especially HCl solution.
• One example of a method for accomplishing this drowning step is as follows. In the drowning vessel (now empty) is placed a volume of water which is approximately five times the volume of the reaction mixture with sufficient HCl to obtain a pH value of 1- 2. If the volume of the vessel does not permit this, the process may have to be accomplished in portions. The reaction mixture is slowly transferred into the drowning vessel with vigorous mixing. This addition is accomplished at a rate such that the temperature of the mixture remains in the range of 10 - 70 degrees C. and preferably in the range of 15 - 20 degrees. HCl is added as needed to keep the pH of the contents of the drowning vessel below 3.
• the particle size of the product depends on the temperature, amount of water used, addition rate of the acid chloride, stirring rate and drowning rate. It is preferred that these parameters be adjusted according to the vessel size and reaction conditions so that optimal particle size is obtained for the product. This means that the particle size is large enough to filter well and is preferably uniform in size. If the particle size is too small the filter may become blocked in the next step.
• the press cake from the filtration process is washed with water until the electrical conductivity of the outlet water is approximately the same as the inlet water. This is conveniently done using tap water initially and then switching to deionized water for the final washes.
• the press cake is squeezed and blown, preferably with nitrogen, to remove more water.
• the product is dried (for example, on a tray dryer) as required.
• a reaction vessel of 11,370 liter capacity is charged with monosodium glutamate (1045.5 kg) dissolved in 2464 liters of water.
• the reaction vessel is purged 3 times with nitrogen at a pressure of 30 psi.
• Full vacuum is applied to the vessel and suction is used to charge 2462 liters of isopropanol. Care is taken to ensure that no air is allowed to be aspirated during this step.
• the vacuum is then broken and the vessel is charged with nitrogen to create a nitrogen atmosphere. Using cooling brine in a jacket around the vessel, the temperature of the contents of the reaction vessel is then lowered to a temperature of 0 - 5 degrees C. A nitrogen bleed is begun to the vessel.
• reaction vessel B containing hcl solution.
• the original reaction vessel (Vessel A) is pressurized with 20 - 30 psi gauge (psig) nitrogen to transfer its contents to Vessel B and excess nitrogen is vented to the scrubber.
• Additional water is added to Vessel A in an amount sufficient to remove the product from Vessel A and rinse the contents of Vessel A into Vessel B.
• the mixture of the contents of Vessel A and the additional water is added to Vessel B in such a manner that the pH is kept below 3.
• this last procedure can be done in 1/4 increments because of the size of the vessels used. Filtration is done between each 1/4 of the material that is processed. In one particular case a total of 7600 gallons ( 28,769 liters) of water and 3176 pounds (1,185.42 kg.) of 31 percent Hcl were used in quater portions.
• the reaction mixture which has just been mixed with the HCl solution is adjusted to a pH of 1.0 - 1.5 with additional HCl.
• the drowned mixture in Vessel B is heated to a temperature of 60 - 65 degrees C and held at this temperature for 30 minutes.
• the mixture is then cooled to ambient temperature (about 25 degrees C.) using brine in the cooling jacket of the reaction vessel.
• the mixture is held at this temperature for 90 minutes.
• the mixture is then filtered, saving the solid and disposing of the filtrate properly.
• the solid on the filter also called filter cake or press cake
• the solid on the filter is washed first with tap water and then with deionized water until the conductivity of the outlet water is approximately the sane as that of the inlet water.
• the press cake is squeezed and blown with nitrogen to remove more water.
• the product is dried on a tray dryer.
• the experimental yield using this procedure is 1539 - 1572 kg (94 - 96 percent) with a purity of about 96 percent,

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Cited By (1)

Citations (2)

• 1996
  • 1996-11-20 ES ES96118530T patent/ES2163572T3/es not_active Expired - Lifetime
  • 1996-11-20 DE DE1996615206 patent/DE69615206T2/de not_active Expired - Fee Related
  • 1996-11-20 EP EP19960118530 patent/EP0844235B1/fr not_active Expired - Lifetime

Patent Citations (2)

Non-Patent Citations (1)

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